Electronic device manufacturers strive to produce a rich interface for users. Conventional devices use visual and auditory cues to provide feedback to a user. In some interface devices, kinesthetic feedback (such as active and resistive force feedback) and/or tactile feedback (such as vibration, texture, and heat) is also provided to the user, more generally known collectively as “haptic feedback” or “haptic effects.” Haptic feedback can provide cues that enhance and simplify the user interface. Specifically, vibration effects, or vibrotactile haptic effects, may be useful in providing cues to users of electronic devices to alert the user to specific events, or provide realistic feedback to create greater sensory immersion within a simulated or virtual environment.
In order to generate vibration effects, many devices utilize some type of actuator or haptic output device. Known haptic output devices used for this purpose include an electromagnetic actuator such as an Eccentric Rotating Mass (“ERM”) in which an eccentric mass is moved by a motor, a Linear Resonant Actuator (“LRA”) in which a mass attached to a spring is driven back and forth, or a “smart material” such as piezoelectric materials, electro-active polymers or shape memory alloys. Haptic output devices also broadly include non-mechanical or non-vibratory devices such as those that use electrostatic friction (“ESF”), ultrasonic surface friction (“USF”), or those that induce acoustic radiation pressure with an ultrasonic haptic transducer, or those that use a haptic substrate and a flexible or deformable surface, or those that provide projected haptic output such as a puff of air using an air jet, and so on.
Pub. No.: US 2014/0251701 A1 discusses about electrostatic adhesion and how it is converted into an application like robotics (wall climbing robot). Electrostatic adhesion has been one of the fundamental force for centuries but recently has received much attention.
Smart electronic devices, such as smartphones are becoming thinner and thinner, but typical electromagnetic based motors that are used to control movements of parts of the devices are relatively bulky and noisy. It is desirable to control forces between moving bodies of smart electronic devices without using conventional motors and actuators. It is also desirable to provide haptic feedback in the next generation of smart electronic devices that are thin and/or flexible.